Strain relief



y 1940. c. T. VON HOLTZ 2,201,213

STRAIN RELIEF Filed Jan. 7. 1938 Patented May 21,1940

UNITED STATES s'rnsnv anus!" Charles Theodore. Von

assignor to Harvey Bridgeport, Conn., necticnt Application January 7,

2 Claims.

This invention relates to new and usefulimprovements in electricaldevices, and has particular relation to a strain reliever for smallattachment plug caps. although it may be used for various devices.

An object of the invention is to provide a relatively smalland':inexpensive attachment plug cap including a strain reliever for thelead connections to the binding screws, and which strain reliever ismounted on the cap without the aid of an extra metal shell or otherpart.

Other objects and advantages will become apparent from a considerationof the following detailed description taken in connection with theaccompanying drawing wherein a satisfactory embodiment of the inventionis shown. However, it is to be understood that the invention is notlimited to the details disclosed but includes all such variations andmodifications as fall within the scope of the invention.

In the drawing: t

Fig. 1 is a top plan view showing the improved plug cap on an enlargedscale;

.Fig. 2 is a side elevational view thereof with 'parts broken away to.show interior construction;

Fig. 3 is a bottom plan view of the cap;

Fig. 4 is a sectional view as along the line H of Fig. l, but with theconnecting cable omitted, and with the strain reliever shown inelevation, the dotted lines in the figure indicating the mannerofapplying and removing the strain reliever; 1

Fig. 5 is a sectional 'view as of along the line 8-5 of Fig. 1;

Fig. 6 is a top plan view of the strain reliever alone; and

Fig. 7 is a side elevational view of the strain reliever alone.

While the invention may be applied in connection with other electricaldevices, it is herein disclosed as embodied in a plug cap.

Referring in detail to the drawing, at It is shown a moulded one piecebody of insulating material, such for example as fBakelite" or similarmaterial, open at its under side as at H, and through its upper sideprovided with an opening i2 for the passage of av cable l3 containingthe lead wires. Within the body and facing the lower open end thereofare shoulders it against which are secured the inner or base portions iiof contact elements or blades it, each such contact element beingprovidedwith a binding post screw II, by means of which, the wires it ofcable I! are connected with the contact elements.

Holtz, Bridgeport, Coma. Hubbell, Incorporated, a corporation ofConisss, Serial No. 183,766

The base portions I 5 are provided'with extensions Ila forced into thebody material to anchor the contacts to the body.

Recesses is are provided in the body between the shoulder portions I4.and such recesses extend radially in opposite directions from the inherend of the opening l2 andsare open at their inner sides, being in thenature'of. radially extending channels. The strain reliever of theinvention comprises a cable clamp generallydesignated 20 and includingsheet metal elements 2| and 22 formed to the proper shape and eachincluding a cable clamping portion and a foot 24 at the inner end of andat right angles to the portion 22.

Strain reliever 20 is mounted on the body .II with cable clampingportions 23 of the reliever extending outwardly through vtheopening i2of the body and with the feet 24 within the body and extending oppositeone another and located in the recesses i9. Ears 25 are formed with andextend laterally from the-edges of clamping portions 23. They arelocated at the outer side of the body and are connected by-screws or thelike 28 adapted to be tightened to draw the elements 2i and 22 towardone another whereby to have the Iportions 23 of such elements clamp thecable 3.

As the feet 24 of the clamping element extend radially with respect tothe opening l2 in the same manner as the recesses it, it will beapparent that the elements 2| and 22 may be moved toward and from oneanother to clamp and release a cable and to accommodate different sizesof cables. The feet 24 are substantially as wide as the recesses It andtherefore while the clamping elements may be moved toward and from oneanother they may not turn relative to the body I 0 and therefore anytwist on the cable It beyond the clamping means will not be transmittedto the binding post connections.

The ears 2! (see Fig. 5) engage or are adjacent the outer surface of thebody as at 21 and thus limit movement of the elements 2| and 22 inwardlythrough the opening I 2, and serve to maintain the feet 24 in engagementor substantially in engagement with the upper walls or surfaces 28 ofthe recesses l9, whereby there is no chance of such feet engaging anyportion of the elements it.

The'clamping elements 2| and 22 are of such size with relation to theopening l2that bytilting such elements (see the dotted lines, Fig. 4)and inserting them with the free endsof their feet 24 foremost and thenafter the feet begin to enter the recesses l9, straightening theelements or bringing the clamping portions 23 toward each other tosubstantially parallel relation, they may be easily and quickly mountedon the body. After the connecting screws 28 are in place, the elements2| and 22 being connected, the strain reliever cannot be removed fromthe body except by first removing the screws 26.

While the elements are connected, the feet 24 extend laterally orradially of the opening l2 in any position of the strain reliever andtherefore these elements cannot be removed from the body so long as oneor both of the screws are in place.

This is fully illustrated in Fig. 4, wherein the screws 26 have beentightened as far as possible and the reliever has been moved as far aspossible toward the left. Yet in such figure .it will be noted that thefoot 24 projecting toward the right has its free end disposed laterallyof or beyond the edge of the opening I2. This is the most contractedposition of the elements but it will be seen they cannot be removed fromthe body as the diameter of the opening I2 is less than the dis tancefrom the outer surface of the clamping portion 23 of one element to thefree end of the leg portion 24 of the other element.

From the foregoing description it will be clear that the strain relieverhas been mounted on the plug cap without the use of an outer metal shellor the like. Thus, the expense of an extra mounting means is avoided,and, in addition, the usual ornamental surface of the moulded body isfully exposed whereby the appearance of the device is not detractedfrom. These features are of a special importance in connection with asmall plug cap.

Having thus set forth the nature of my invention, what I claim is:

1. In a device of the character described, an integral moulded one-piecebody of insulating material, lead wire connections carried by said body,said body having an opening leading to said connections, a cable clampincluding a pair of elements extending through said opening and eachcomprising a cable clamping portion and an angularly related foot withinsaid body and extending radially relative to said opening, meansconnecting said clamping portions for causing them to clamp a cablepassing through said opening, said body having internal recessesextending radially from said opening having bottom walls spaced inwardlyfrom the outer wall through which the opening enters and facing in theopposite direction from this wall, said recesses being open at theirinner sides and receiving said feet to cooperate with said bottom wallswhereby the clamping elements may move toward and from one another butare held against removal from necting portion of one element and thefree end of the foot of the other element when saidclamping portions areconnected and of a size to permit each element to be rocked about theedge of the opening to permit insertion and removal of the foot throughthe opening when the elements are disconnected.

2. In a device of the character described, a connector cap comprising amolded one-piece body of insulating material open at one side and provided withshoulders spaced inwardly from said open side and facing saidopen side, contact elements comprising base portions mounted on saidshoulders and blade portions projecting from. said open side of the bodyand means for connecting lead wires to said elements, said body beingprovided with an opening leading therethrough from the opposite side tosaid shoulders for passage of a cable containing lead wires forconnection to said elements, said body having a pair of recessesextending inwardly from said shoulders and laterally in oppositedirections from said opening and having bottom walls spaced inwardlyfrom said shoulders, a pair of clamping elements mounted in said openingand each comprising a curved body adapted to be clamped against thecable and an angularly related substantially fiat foot at its inner endextending radially in one of said recesses relative to said opening toengage the bottom wall of the recess and slide thereon with the sidewalls of the recesses cooperating with the edges of the foot portions toprevent turning of the clamping elements in the body, cooperating meanson the clamping elements and the body to limit inward movement of saidelements in the opening, means connecting the body portions of theclamping elements to clamp them against a cable, and said feet being ofsuch a size with respect to the, opening that when said connectingmeansare disconnected the elements may be tilted about the edges of theopening and the feet passed through the opening to or from a position inthe recesses and when the elements are connected by said means said feetextend laterally beyond the edges of the opening to engage the bottomwalls of the recesses in all positions of the elements to prevent theirremoval from the opening.

CHARLES THEODORE VON HOLTZ.

